The television broadcasting industry is under transformation. One of the agents of change is television transmission over Internet Protocol (IPTV). In IPTV, a television viewer receives only selected content. The playback of IPTV requires either a personal computer or a “set-top box” (STB) connected to an image projection device (e.g., computer screen, television set). Video content is typically an MPEG2 or MPEG4 data stream delivered via IP Multicast, a method in which information can be sent to multiple computers when these computers join the IP multicast address to which the selected content is being sent. IP multicast is based on Internet Group Management Protocol (IGMP) described in RFC 2236 and its successor for version 3. In comparison, in legacy over the air television broadcasting, a user receives all broadcast content and selects one via a local tuner. Television broadcasting over cable and over satellite follows the same general principle using a wider bandwidth providing for a larger choice of channels.
In IPTV, the content selection of live content is made by registering an address of the viewer to a multicast group using standardized protocols (e.g., IGMP version 2). Live content include the typical over the air, cable or satellite content. Quality of Service (QoS) of the IPTV contents is guaranteed. As such, new content should be delivered to a requesting viewer (or admitted in the transit and access networks) only if it does not affect content being currently delivered to other users through the above networks.
A problem occurs since the usual admission control mechanisms are based on unicast contents, which present linear resource use in a network (i.e., all links between the source and the destination equally affected). Multicast, on the other hand, is replicated by intermediate routers on a need basis (i.e., presence of a consumer of the content on a downlink path). This creates a multicast distribution tree that optimizes resource use. Current admission control mechanisms fail to properly take into consideration multicast optimization.
The problem described in terms of IPTV in the preceding lines is also present in other technologies where a data feed is to be distributed via multicast. For instance, similarities may be readily observed with other TV or audio contents such as Mobile TV, High Definition Digital content, Digital Video Broadcasting Handheld (DVBH), various radio streaming, MP3 streams, private or public surveillance systems streams (audio or video or audio-video), etc. Some other examples also include a given file in high demand (new software release, software update, new pricing list, new virus definition, new spam definition, etc.). There could also be other examples of situation in which a similar problem occurs.
A further problem of current admission control mechanisms is limited scalability. When a stream traverses many administrative domains, its admission control in one of all traversed administrative domains does not guarantee overall admission control.
As can be appreciated, it would advantageous to be able to properly handle multicast admission control and to further support scalability or at least does not limit scalability as much as current situations. The present invention aims at providing at least a portion of the solution to the problem.